biogas potential of organic wastes Wroclaw, November 2011 Thorsten Ahrens Ostfalia University of Applied Sciences, Germany

Transcription

1 biogas potential of organic wastes Wroclaw, November 2011 Thorsten Ahrens Ostfalia University of Applied Sciences, Germany

2 INTRODUCTION UNIVERSITY OF APPLIED SCIENCES, WOLFENBÜTTEL, GERMANY 2

3 TASKS WITHIN REMOWE PROJECT biogas potential of different waste substrates and waste substrate mixtures including possible pre-treatment strategies report on biogas utilization strategies (including waste utilization, digestion technology and residue treatment) for each individual region - to be used by authorities and companies for decisions on investments in technology and systems and for policy making in the project contribute to the investigation of the current status in the whole chain of waste-to-energy utilization in each partner region and the current conditions and systems from which the development has to start 3

4 ORIGIN & KIND OF SUBSTRATES Finland: Iisalmi: hay silage (various ages) Kuopio: municipal waste (30mm), unsorted organic waste manure and wood chips Estonia, Tallinn: edible fat waste from grease traps organic waste brewers grains waste water paper pulp Sweden, Västeras: organic waste, ley crops silage unsorted municipal waste Poland, Gac: municipal waste, fraction <80 mm; <60 mm; mm Lithuania: Klaipeda, waste water sludge Siauliu region, dump waste Taurage region, dump waste Plunges region, dump waste Klaipeda, dump waste Kretinga region, cow manure palm oil, waste from spirit distillation, waste from screeners

5 VARIATION OF SUBSTRATES dumped waste waste water sludge animal faeces biowaste agricultural (over)products municipal household waste industrial organic waste 5

6 DENIED SUBSTRATES FOR CONTINUOUS TESTS dumped waste waste water sludge animal faeces biowaste agricultural (over)products municipal household waste industrial organic waste 6

7 DENIED SUBSTRATES FOR CONTINUOUS TESTS hay paper pulp animal tissues unsorted municipal waste high ratio of non digestable material (e.g. lignin) high health and safety at work effort not suitable for wet fermentation 7

8 PROCEDURE OF WORK STEPS batch fermentation tests to gain maximum methane potential selection of suitable substrates or substrate mixtures for continuous tests also depending on needs for digestate disposal and pre-sorting sanitation 8

9 PROCEDURE OF WORK STEPS starting of continuous fermentation tests (duration ~3 months) verifying methane potentials from batch tests detecting process problems (overfeeding, acidification, layer forming, clogging of process technology) comparison of methane potential with common agricultural substrates 9

10 RESULTS BATCH TESTS paper pulp nearly no methane production biowaste good methane production 10

11 RESULTS BATCH TESTS (EXTRACT) Estonian substrates date (2011) sample EWC code temp. conditions Nm 3 (CH 4 )/ Mg(fresh mass) Nm 3 (CH 4 )/ Mg(oDM) methane content in Vol-% January paper pulp mesophil January paper pulp mesophil January brewers' grains mesophil January brewers' grains mesophil January grease traps waste mesophil January grease traps waste mesophil January edible fat mesophil January edible fat mesophil January kitchen & canteen waste mesophil January kitchen & canteen waste mesophil March Estonian Mix , , mesophilic March Estonian Mix 2 25, mesophilic

12 CONCLUSIONS CONCERNING BATCH TESTS 34 double tests performed dumped waste waste water sludge animal faeces biowaste agricultural (over)products high effort to be prepared, low methane output high water content, on-site fermentation recommended recommended as co-substrate compositions vary throughout seasons, good methane yield methane yield depend on age of agricultural products municipal household waste high effort to be prepared, outsourcing of disturbants, sanitation necessary industrial organic waste high methane potential, high process attention necessary, suitable as co-substrate 12

13 RESULTS CONTINUOUS TESTS Estonian substrates mixed for continuous tests 13

14 RESULTS FROM CONTINUOUS TESTS (EXTRACT) substrate Estonia Finland Lithuania Sweden brewers grains, edible fat, biowaste, grease trap waste municipal household waste cow manure, sewage sludge, screenings, waste from spirit distillation, palm oil biodegradable kitchen & canteen waste pre-sorting testing period (d) total substrate in (g) 3,160 9,813 11,508 9,216 total substrate out (g) 3,195 6,963 9,939 7,148 range of organic load range weight of substrate (g) effects through sanitation - Ø final odm of digestate (% of FM) recommendation concerning dry fermentation process stability Ø stable methane production (NL/h) 14

15 CONCLUSIONS CONCERNING CONTINUOUS TESTS all substrates tested in continuous reactors performed successfully digestion analyses have been performed recommendations concerning digestion suitability can be defined obstacles concerning digestion process could be defined 15

16 SUMMARY OF ENERGY POTENTIALS methane productivity from biogas processes heating value and energy from digestate through combustion Estonia Finland Lithuania Sweden n.a. (**) Ø methane production from lab-scale (Nm 3 /t odm) annual substrate amount n.a (t/a) substrate s odm (%FM ) energy content CH (kwh/m 3 ) annual energy from biogas n.a (MWh/a) annual digestate amount (*) n.a (t/a) digestate s DM (%FM ) heating value (kwh/kg DM) annual energy from digestate n.a (MWh/a) percentage digestate energy of biogas n.a. energy (%) (**) digestate = 85 % of substrate amount (**) no information about yearly waste amounts 16

17 RESULTS FROM DIGESTATE ANALYSES (EXTRACT) heavy metal analyses (Estonian continuous tests) limit (mg/kg DM) reactor 1 reactor 2 (mg/kg DM) (mg/kg DM) (mg/kg DM) chrome (Cr) n.a. at the moment copper (Cu) nickel (Ni) zinc (Zn) cadmium (Cd) lead (Pb) mercury (Hg) ammonium results (Estonian continuous tests) inoculum reactor 1 reactor 2 dairy cow manure (*) NH 4 (g/l) P (g/kg) N (g/kg) (*) (Chamber of Agriculture Lower Saxony, 2009) sow manure (*) concentration of impurities (Finnish continuous tests) reactor 1 reactor 2 top layer % % middle layer % % bottom layer % % stirrer % % average value % % 17

18 CONCLUSIONS most substrates are suitable for biogas (wet digestion) reliable data as basis for calculation available data basis for process upscaling by-products are usable AND OUTLOOK finding and discussion of implementation strategies calculation of degree of energy substitution for each region kind of utilization (biomethane, electricity, heat) discussion of side-effects (fertilizer/climate) 18

19 sewage sludge fermentation batch test 19 gas measuring: volume and composition daily shaking heating cabinet, 35 days, 40 C